38,865 research outputs found
The gluon propagator from large asymmetric lattices
The Landau-gauge gluon propagator is computed for the SU(3) gauge theory on
lattices up to a size of . We use the standard Wilson action
at and compare our results with previous computations using large
asymmetric and symmetric lattices. In particular, we focus on the impact of the
lattice geometry and momentum cuts to achieve compatibility between data from
symmetric and asymmetric lattices for a large range of momenta.Comment: Poster presented at Lattice2007, Regensburg, July 30 - August 4, 200
Phase transitions and statistical mechanics for BPS Black Holes in AdS/CFT
Using the general framework developed in hep-th/0607056, we study in detail
the phase space of BPS Black Holes in AdS, for the case where all three
electric charges are equal. Although these solitons are supersymmetric with
zero Hawking temperature, it turns out that these Black Holes have rich phase
structure with sharp phase transitions associated to a corresponding critical
generalized temperature. We are able to rewrite the gravity variables in terms
of dual CFT variables and compare the gravity phase diagram with the free dual
CFT phase diagram. In particular, the elusive supergravity constraint
characteristic of these Black Holes is particulary simple and in fact appears
naturally in the dual CFT in the definition of the BPS Index. Armed with this
constraint, we find perfect match between BH and free CFT charges up to
expected constant factors.Comment: 14 pages, 5 figures, corrected typos and references adde
On the finiteness of the noncommutative supersymmetric Maxwell-Chern-Simons theory
Within the superfield approach, we prove the absence of UV/IR mixing in the
three-dimensional noncommutative supersymmetric Maxwell-Chern-Simons theory at
any loop order and demonstrate its finiteness in one, three and higher loop
orders.Comment: 9 pages, 2 figures, revtex
Adaptação de um conjunto de pulverizador: vibronivelador para incorporação simultânea de tiocarbamatos.
Temperature dependence of antiferromagnetic susceptibility in ferritin
We show that antiferromagnetic susceptibility in ferritin increases with
temperature between 4.2 K and 180 K (i. e. below the N\'{e}el temperature) when
taken as the derivative of the magnetization at high fields (
Oe). This behavior contrasts with the decrease in temperature previously found,
where the susceptibility was determined at lower fields ( Oe). At
high fields (up to Oe) the temperature dependence of the
antiferromagnetic susceptibility in ferritin nanoparticles approaches the
normal behavior of bulk antiferromagnets and nanoparticles considering
superantiferromagnetism, this latter leading to a better agreement at high
field and low temperature. The contrast with the previous results is due to the
insufficient field range used ( Oe), not enough to saturate the
ferritin uncompensated moment.Comment: 7 pages, 7 figures, accepted in Phys. Rev.
HYDROGEN PRODUCED BY SOLAR ENERGY AND THEIR USE AS CLEAN FUEL FOR POWER GENERATION IN A COMBINED CYCLE POWER PLANT
The solar energy is one of the most promising energy sources expected for the future, due at their huge potential and the wide availability around the world. However, nowadays this important source of energy is not being harnessed or even addressed in their full potential. According to the last statements, it is important to develop solar energy conversion systems of high efficiency, as well as spreading its use in other forms besides the traditional systems of electric power generation or heating systems. For this reason, in this paper, it is explored the production of hydrogen through solar energy utilization, and the later electrical energy production by burning the produced hydrogen in a combined cycle power plant. The process was modelled for 3 MWe of electricity generation, and using the organic Rankine cycle. The main process for producing hydrogen from water using solar energy is based on a two steps redox thermochemical cycle, which has a theoretical conversion efficiencies of 54% at 1600 K. It is expected that this paper could contributed to the development of ways to enable a better integration of the solar energy with the current electricity generation technologies, as well as to incentive the use of the hydrogen as a clean fuel
LSDA+U approximation-based analysis of the electronic estructure of CeFeGe3
We perform ab initio electronic structure calculations of the intermetallic
compound CeFeGe3 by means of the Tight Binding Linear Muffin-Tin
Orbitals-Atomic Sphere Approximation (TB-LMTO-ASA) within the Local Spin
Density Approximation containing the so-called Hubbard correction term
(LSDA+U^SIC), using the Sttutgart's TB (Tight Binding)-LMTO-ASA code in the
framework of the Density Funcional Theory (DFT).Comment: 12 pages 8 figures, submitted to Int. J. Modern Phys.
The Noncommutative Supersymmetric Nonlinear Sigma Model
We show that the noncommutativity of space-time destroys the
renormalizability of the 1/N expansion of the O(N) Gross-Neveu model. A similar
statement holds for the noncommutative nonlinear sigma model. However, we show
that, up to the subleading order in 1/N expansion, the noncommutative
supersymmetric O(N) nonlinear sigma model becomes renormalizable in D=3. We
also show that dynamical mass generation is restored and there is no
catastrophic UV/IR mixing. Unlike the commutative case, we find that the
Lagrange multiplier fields, which enforce the supersymmetric constraints, are
also renormalized. For D=2 the divergence of the four point function of the
basic scalar field, which in D=3 is absent, cannot be eliminated by means of a
counterterm having the structure of a Moyal product.Comment: 15 pages, 7 figures, revtex, minor modifications in the text,
references adde
Angular Power Spectrum Estimation of Cosmic Ray Anisotropies with Full or Partial Sky Coverage
We study the angular power spectrum estimate in order to search for large
scale anisotropies in the arrival directions distribution of the highest-energy
cosmic rays. We show that this estimate can be performed even in the case of
partial sky coverage and validated over the full sky under the assumption that
the observed fluctuations are statistically spatial stationary. If this
hypothesis - which can be tested directly on the data - is not satisfied, it
would prove, of course, that the cosmic ray sky is non isotropic but also that
the power spectrum is not an appropriate tool to represent its anisotropies,
whatever the sky coverage available. We apply the method to simulations of the
Pierre Auger Observatory, reconstructing an input power spectrum with the
Southern site only and with both Northern and Southern ones. Finally, we show
the improvement that a full-sky observatory brings to test an isotropic
distribution, and we discuss the sensitivity of the Pierre Auger Observatory to
large scale anisotropies.Comment: 16 pages, 6 figures, version accepted for publication by JCA
Endoparasitos do pacu-manteiga Mylossoma duriventre Cuvier, 1817 (Characidae) do lago Coari, região do Médio Rio Solimões, Estado do Amazonas.
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